Kinematics Question 401
Question: A man throws balls with same speed vertically upwards one after the other at an interval of 2 sec. What should be the speed of throw so that more man two balls are in air at any time?
Options:
A) Only with speed 19.6 m/s
B) More than 19.6 m/s
C) At least 9.8 m/s
D) Any speed less than 19.6 m/s.
Show Answer
Answer:
Correct Answer: B
Solution:
Height attained by balls in 2 sec is $ =\frac{1}{2}\times 9.8\times 4=19.6\text{ m} $ The same distance will be covered in 2 second (for descent) Time interval of throwing balls, remaining same. So, for two balls remaining in air, the time of ascent or descent must be greater than 2 seconds. Hence speed of balls must be greater than $ 19.6m/sec $ .
